Electrical switching means

ABSTRACT

An electrical switching assembly has a temperature-responsive bimetal for completing an electrical circuit with a cooperating switch terminal member which can be variably positioned in order to achieve the making and breaking of a related circuit at a predetermined temperature. Modifications of such a switch assembly include the provision of controlled hysteresis within the bimetal in order to result in the making of the circuit therethrough to occur at an environmental temperature different from the environmental temperature at which the circuit therethrough is opened.

United States Patent Aloysius Joseph Kochan'ski 27312 Spring Arbor Drive, Southfield, Mich. 48075;

Charles John Hire, 6 Cranswick Lane, Rochester, N.Y. 14618 [21] Appl. No. 879,648

[22] Filed Nov. 25, 1969 [45] Patented Nov. 2, 1971 [72] Inventors [54] ELECTRICAL SWITCHING MEANS 9 Claims, 22 Drawing Figs.

[52] US. Cl 337/380, 337/374, 337/379 [51] Int. Cl 1101b 37/04, HOlh 37/28, l-lOlh 37/52 [50] Field of Search 200/ 166 CM, 166 B, 166 CT, 166.1; 337/1 12, 113, 347, 360, 370, 371, 373, 374, 379, 380, 381,111

[56] References Cited UNITED STATES PATENTS 3,352,986 i H1967 Doherty, Jr

3,234,350 2/1966 Johnson et aL 337/380 X 3,171,933 3/1965 Webb etal 337/380X 3,148,258 9/1964 Dales 337/381 X 2,820,870 1/1958 Moksu 337/381 X 2,759,066 8/1956 Short et al. 337/373 X FOREIGN PATENTS 1,341,981 9/1963 France 337/380 Primary Examiner-Bernard A. Gilheany Assistant Examiner-Dewitt M. Morgan Attorney- Lon H. Romanski ABSTRACT: An electrical switching assembly has a temperature-responsive bimetal for completing an electrical circuit with a cooperating switch terminal member which can be variably positioned in order to achieve the making and breaking of a related circuit at a predetermined temperature. Modifications of such a switch assembly include the provision of controlled hysteresis within the bimetal in order to result in the making of the circuit therethrough to occur at an environmental temperature different from the environmental temperature at which the circuit therethrough is opened.

PATENTEDNUVZ 1971 3617874 sum 2 OF 3 PRIO F2 ART 150a lNVI-INIHRS AZqysz'as J Kocizamkz', Char! J. A're ATTORNEY ELECTRICAL SWITCHING MEANS BACKGROUND OF THE INVENTION Because though recent governmental regulations and a general concern for the elimination and/or reduction of atmospheric pollutents great efforts have been expended by the automotive industry in devising engine and carburetor improvements which would at least substantially reduce the degree of emission of unburned hydrocarbons into the atmosphere. For example, one of the major advances of the industry has been the development of what is commonly referred to as a positive crankcase ventilation (ICV) system which, in essence, ventilates or communicates the engine crankcase fumes to the engine intake in order to further such fumes instead of merely freely venting such fumes to the atmosphere as has been done in the past.

Generally, internal combustion engines will produce an emission of unburned hydrocarbons and other pollutents into the atmosphere in proportion to the degree that there is incomplete combustion of the fuel. Accordingly, it should be apparent that the occasion for such unburned fuel to exist would occur more often during engine and vehicle acceleration, when such carburetor components as the accelerating pump are employed to dump extra quantities of fuel into the induction passage, and during cold engine starting and subsequent warmup when the carburetor choke is in a more nearly closed position causing a greater rate of fuel flow to the engine.

It has been discovered that engine exhaust emission of atmosphere pollutents occurring as a consequence of the above conditions can be greatly reduced by varying the ignition spark timing in order to provide an additional length of time for the burning of the fuel within the engine. For example, if the ignition timing is advanced in a cold engine at curb idle operation, the ignition within the engine cylinder will occur at some number of degrees of crankshaft rotation ahead of when the piston reaches its top-dead-center position (the amount of ignition advance will determine the number of degrees of crankshaft rotation). This, therefore, permits more time for the burning of the fuel within the cylinder before the expansion and exhaust portion of the engine operating cycle occurs.

In order to achieve such controlled override or advance of the ignition spark timing mechanism, it has been determined that electrical switching means sensitive to the occurrence of upper and lower predetermined critical engine temperatures is necessary in order to provide the necessary switching functions related to the regulation of the ignition timing mechanism.

However, the electrical switching assemblies of the prior art have been found to be generally unsatisfactory for many reasons. First, such prior art switch assemblies are difficult (and consequently costly) to calibrate with the precision necessary in order to make and break the control circuits at precisely the predetermined critical engine temperatures. Further, the prior art electrical switches have usually failed to transmit a warning signal sufficicntly quickly, as when a watercooled engine has lost its coolant due to some leakage, to prevent permanent damage to the engine. Also, many of the prior art switches, employing thermostatic switching elements, exhibit a degree of instability; that is, the switch tends to make and break the electrical circuit at approximately the same environmental temperature thereby causing instability in the control circuit.

Accordingly, the invention as herein disclosed and described is directed to the solution of the above as well as other attendant problems.

SUMMARY OF THE INVENTION According to the invention, a temperature-responsive electrical switch assembly, comprises a housing, an insulating member closing one end of said housing and defining a chamber within said housing, first switch contact 62 carried by said insulating member and having a first contact portion extending into said chamber, said first switch contact means including a second terminal portion extending beyond said insulating member externally of said chamber, electrically conductive temperature-responsive responsive means carried by said housing within said chamber, said first switch contact means being longitudinally adjustable in order to permit movement thereof relative to said insulating member and said temperature-responsive means to a suitable position in order to enable engagement between said temperature-responsive means and said first contact portion at a predetermined temperature, and means carried by said insulating member for effectively locking said first switch contact means against further longitudinal movement once said switch contact means has been moved to said position.

Accordingly, a general object of the invention is to provide a temperature-responsive electrical switch which can, during its manufacture, be quickly calibrated in order to make and break an electrical circuit at a predetermined temperature.

Another object of the invention is to provide a particular control circuit in combination with an internal combustion engine for exercising a control function over the related ignition spark timing control mechanism.

Other more specific objects and advantages of the invention will become apparent when reference is made to the following detailed description considered in conjunction with the accompanying drawings.

DESCRIPTION OF THE DRAWINGS In the drawings, wherein for purposes of clarity certain details may be omitted from one or more views:

FIG. 1 is a side elevational view of an internal combustion engine and ignition distributor assembly employing electrical circuitry in accordance with the invention;

FIG. 2 is an enlarged fragmentary portion of the schematic wiring diagram of FIG. 1;

FIG. 3 is an enlarged somewhat simplified view, in crosssection, of certain elements of FIG. 1;

FIG. 4 is an enlarged cross-sectional view of the switch assembly of FIG. 1 constructed in accordance with the teachings of the invention;

FIG. 5 is a view taken generally on the plane of line 5-5 of FIG. 4, with portions thereof broken away;

FIG. 6 is an enlarged fragmentary cross-sectional view taken generally on the plane of line 6-6 of FIG. 4 and looking in the direction of the arrows;

FIG. 7 is a fragmentary cross-sectional view taken generally on the plane of line 7-7 of FIG. 4;

FIG. 8 is a partial cross-sectional view of a switch assembly, constructed in accordance with the prior art, situated within, for example, a wall of an engine employing liquid coolant;

FIG. 9 is a view similar to FIG. 8 but illustrating a switch assembly constructed in accordance with the teachings of the invention;

FIG. 10 is an enlarged elevational view, with portions broken away and in cross section, illustrating modifications of the switch assembly of FIG. 4;

FIG. l0-A is a fragmentary cross-sectional view of another embodiment of a switch assembly which might be considered a modification, in reduced scale, of that shown in FIG. 10;

FIG. 11 is a fragmentary cross-sectional view taken on the plane ofline 11-11 ofFlG. 10;

FIG. 12 is a fragmentary cross-sectional view of the switch assembly FIG. 10 illustrating a further modification;

FIG. 13 is a fragmentary perspective view of a thermostatic element employable within the invention;

FIG. 14 is a longitudinal cross-sectional view of another embodiment of the switch assembly of the invention;

FIG. 15 is an enlarged fragmentary cross-sectional view taken generally on the plane of line 15-15 of FIG. 14;

FIG. 16 is a longitudinal cross-sectional view of another embodiment of a switch in accordance with the invention;

FIG. 17 is a transverse cross-sectional view taken generally on the plane of line 17-17 of FIG. 16, in the direction of arrows;

FIG. 18 is a generally longitudinal cross-sectional view taken on the plane of line 18-18 of FIG. 16;

FIG. 19 is a perspective view of one of the elements disclosed within FIGS. 16, 17 and 18;

FIG. 20 is a fragmentary elevational view illustrating a modified form of the thermostatic elements of FIGS. 4, 10, 14, or 16;

FIG. 21 is a fragmentary elevational view typically showing an additional modified form of the end of the thermostatic element as shown, for example, in FIG. 20.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now in greater detail to the drawings, FIG. 1 illustrates a vehicular internal combustion engine having an intake manifold 12 on which is mounted a suitable carburetor assembly 14 provided with an air cleaner assembly 16. An ignition distributor assembly 18, having a first vacuum motor 20 for normally controlling the ignition spark advance and retard and a second vacuum motor 21 operatively connected to the first vacuum motor 20 for at times overriding the normal ignition retard, is driven in timed relation to engine speed in an manner well known in the art. As shown, the engine 10, in addition to having a power transmission assembly 22 connected thereto, may be provided with such other engine-driven accessories as, for example, a compressor 24 which may be associated with a vehicular air-conditioning system. The compressor 24 may be driven through a clutch assembly 26 receiving its power through belt means 28 looped about sheaves 30 and 32 respectively connected to the clutch input shaft 34 and an engine crankshaft 36. A first conduit 38 leading from vacuum motor 21 is connected to branch conduits 40 and 42 respectively leading to a vacuum port 43 (which, as illustrated may be communicating with the interior of the intake manifold 12) and to one side of a solenoid valve assembly 44 the other side of which may be provided with suitable conduit means 46 leading to a source of atmospheric air as, for example, within the air-cleaner assembly 16. A second conduit 45 communicates at one end with vacuum motor 20 and at its other end with suitable porting means within the carburetor 14. Such porting means, as is well known in the art, may be placed in controlled communication with engine vacuum in accordance with throttle valve position in order to thereby vary the degree of vacuum to therein motor 20.

As is somewhat diagrammatically illustrated in FIG. 1, the transmission assembly 22 is provided with a switch assembly 48 having first and second terminals 50 and 52 which are respectively electrically connected to electrical conductors 54 and 56 with conductor 54 being suitably grounded as at 58. A second switch assembly 60, carried by a suitable portion of the engine assembly 10, is provided with a plurality of terminals 62, 64, and 66 which are respectively electrically connected to conductors 68, 56 and 70. As shown, conductor 68 is connected as at 72 to conductor 56 while conductor 70 is connected to one terminal of an engine temperature warning device, such as an electrical bulb 74, which may be located within the vehicular passenger compartment as on, for example, the instrument or dash panel 76.

Terminals 78 and 80 of solenoid valve assembly 44 are respectively electrically connected to conductors 82 and 84 which, in turn, are respectively connected to conductor 56, as at 86, and to one terminal 88 of a switch assembly 90 having its switch member 92 connected to one electrical side of a suitable source of electrical potential 94. The other electrical side of electrical source 94 may be connected to ground potential as at 96. The other terminal of bulb 74 may be connected as by a conductor 98 to conductor 84 as at 100.

FIG. 2, a rather simplified wiring diagram of the circuitry of FIG. 1, illustrates the solenoid assembly 44 as comprising a housing or body portion 102 having conduit portions 104 and 106 formed therein with a valve seat portion 108 between conduits 104 and 106 which are respectively in communication with conduits 46 and 42 of FIG. 1. The solenoid assembly 44 also includes a corelike valving member 110 provided with a valve surface 112 adapted to at times engage the valve seat 108. A resilient member or spring 114 normally urges the valving member in a direction away from valve seat 108. However, the winding or coil 116, when energized through conductors 84 and 56, is effective to cause valving member 110 to move downwardly, against the resistance of spring 114, so as to seat against the valve seat 108.

Before progressing to the description of the other Figures, it might be best to first further define the operation of vacuum motors 20 and 21 illustrated in FIGS. 1 and 3. As is well known in the art, vacuum motor 20 may be comprised of housing sections 17 and 19 between which is retained a pressure-responsive diaphragm member 27 operatively connected to the spark advance mechanism within the housing of distributor assembly 18 as by linkage means 29. Usually housing section 17 is vented to the atmosphere while housing section 19 is placed in controlled communication with a source of vacuum as by the conduit 45. Spring means are employed for normally placing the ignition spark advance mechanism within the ignition distributor assembly 18 in full retard during such periods of operation wherein no or substantially no vacuum is communicated to housing section 19 as, for example, during curb-idle engine operation. However, as the throttle valve within the carburetor 10 is progressively moved toward a more nearly wide-open position a greater degree of vacuum is communicated to housing section 19 and applied to the diaphragm 27 therein causing such diaphragm to progressively move, in accordance with the valve of the vacuum, and thereby effect some degree of advance in the ignition spark timing. The same is also true as the engine speed increases because the conduit means 45 is usually also connected to a vacuum sensing port within the venturi throat of the carburetor induction passage.

Similarly, vacuum motor 21 is comprised of housing sections 23 and 25 with a pressure-responsive diaphragm 3l retained therebetween. Housing section 23 would be vented to the atmosphere while housing section 25 would be placed in controlled communication with a source of vacuum as by conduit means 40. Even though not shown, but as well known in the art, a lost-motion connecting linkage 33 operatively interconnecting the two diaphragms 27 and 31 of the motors 20 and 21 permits the first motor 20 diaphragm 27 to be. fully responsive to vacuum within housing section 19 while enabling diaphragm 31 with motor 21 to forcibly move the motor 20 diaphragm 27 some predetermined distance in the spark advance direction whenever the motor 20 diaphragm 27 is in its maximum or full retard condition and vacuum is directed to housing 25. Generally, since solenoid valve 112 is normally open and therefore venting conduit 42 to atmospheric pressure motor 21 diaphragm 31 will not be exposed to a sufiiciently reduced pressure as to be in any way effective for influencing the position of the motor 20 diaphragm 27. To this end, if desired, a suitable calibratinglike restriction may be placed within conduit means 40 at a point somewhere between the vacuum port 43 and the juncture of conduits 38 and 40. However, when valve 112 is closed against seat 108, the atmospheric bleed is closed thereby enabling the full vacuum to be applied to motor 21 diaphragm 31 in order to thereby cause the previously described predetermined ignition spark timing advance. The vacuum motors 20 and 21 have been, for purposes of clarity, illustrated as being in a tandom arrangement; however, it should be apparent that such pressure responsive motors may be situated separately from each other and independently connected to the ignition timing mechanism situated within the distributor assembly 18.

Referring now in greater detail to the remaining FIGS., FIG. 4 illustrates the switch assembly 60 as comprising a generally cup-shaped housing or body having an externally threaded portion 122 for threadably engaging a cooperating internally threaded portion 124 of the engine 10. A generally U-shaped bimetallic or thermostatic element 126, having arm portions 128 and 130 joined by a bight portion 132, may be suitably retained in the housing chamber 134 and secured to the lower end wall 136 of said housing as by an upstanding peened-over anchor portion 138 formed integrally with housing 120.

The upper end of chamber 134 is closed off by an electrically nonconductive platelike cap 140 which has a plurality of apertures 142, 144 and 146 formed therein for closely respectively receiving the terminal members 62, 64 and 66 therethrough. As shown, the upper end of housing 120 is formed with an interior shoulder portion 148 against which the terminal mounting plate 140 is situated and securely held in place as by rolled-over or peened clamping portions 150. Such portions 150 may be a continuous ringlike configuration or a plurality of individual fingerlike members formed integrally with the body 120. As shown, a sealing member 152, coextensive with the lower surface of cover 140 and preferably extending some amount upwardly about the edge thereof, is provided between the shoulder 148 and the lower surface of cover 140. If desired, a second annular seal 153 may be provided between the clamping portions 150 and the upper surface of terminal mounting plate 140.

As can be seen, the lower ends of terminal members 62, 64

and 66 are respectively formed to have ramplike or vertically inclined contact surfaces 154, 156 and 158, while the main body portions of the terminal members may be provided with longitudinally extending keylike portions 160 and 162 closely slidably received in cooperating relieved portions 164 and 166 formed through cover 140.

As should be apparent, the temperature at which the arms 128 and 130 will engage the inclined terminal contacting surfaces 154, 156 and 158 will depend on whether the terminal members 62, 64 and 66 are moved either upwardly or downwardly from the positions shown. Accordingly, after the calibration of the switch elements, that is, the determination of the relative vertical positions of terminal members 62, 64 and 66 in order toachieve switching functions at predetermined temperatures, the space 168 above the cover plate 140 is filled with a suitable electrically nonconductive material 170, such as an epoxy resin, which serves to hermetically seal the inner chamber 134 and to lock the respective terminal members 62, 64 and 66 into their previously determined calibrated positions. As best shown in FIG. 5, the upper end of housing 120 is preferably provided with a toolengaging surface 172 by which the switch assembly 60 can be tightly threadably engaged with a cooperating portion of the engine 10.

As typically illustrated by terminal member 62 of FIG. 6, each of the terminal members may be provided with a blade or spadelike terminal contact portion 174 for connection to a suitable cooperating female type electrical connector as might be carried, for example, by conductors 68,56 or 70 of FIG. 1.

As best shown in FIGS. 6 and 7, the bight portion 132 of bimetallic element 126 may be of an enlarged configuration, in plan view, and, further, may have a notchlike cutout portion 176 for the reception therein of an upstanding keylike abutment portion 178 formed integrally with the end wall 136. The purpose of the cutout 176 and coacting abutment 178 is to provide a means for both positioning and maintaining such position of the bimetallic element within the housing 120.

OPERATION OF THE INVENTION In view of the above, the general operation of the invention is as follows. For purposes of illustration let it be assumed that it has been determined that full or maximum retard of the ignition timing is not desired at engine temperatures equal to or less than 60 F. nor at engine temperatures equal to or greater than 250 F. Now let it be further assumed that the engine had been previously operating at a temperature range between 60 F. and 250 F. and that such engine has just been shutdown. At this time bimetal arms 128 and 130 would be in a position generally as illustrated in FIG. 4.

However, if it is now assumed that the engine has cooled to be at an ambient temperature of, for example, 40 F. the thermostatic arm 128 will have moved generally to the left so as to engage terminal contact portion 154. If the engine is now started, an electrical circuit is completed starting from ground 96 (FIG. 1), electrical source 94, conductor 84, terminal 80, solenoid winding 116 (FIG. 2), terminal 78, conductor 56, conductor 68, switch terminal members 62 and ramp contact portion 154 (FIG. 4), bimetal arm 128, bight portion 132, retainer 138 and housing base 136, and back to ground at 180 (FIG. 4). The energization of coil 116 causes valve member 112 to seat against orifice 108 thereby closing the atmospheric vent or bleed to conduit 42. Consequently, the manifold vacuum from source 43 can be applied to motor 21 diaphragm thereby causing that diaphragm to move motor 20 diaphragm a predetermined distance in order to thereby effect a like predetermined degree of ignition timing advance.

As long as the engine temperature, as sensed by bimetal arm 128 remains at or below 60 F. the above-described circuit will remain closed and the ignition timing mechanism will be prevented from going to a full retard position. However, if the vehicle is driven away from curb-idle while still at temperatures below 60 F., additional degrees of ignition timing advance are of course possible due to the action of motor 20 diaphragm 27 depending upon such parometers as engine load, throttle valve position and engine speed each of which as is well known in the art, will influence the strength of the vacuum applied via conduit 45 to vacuum motor 20.

When the engine temperature exceeds 60 F., bimetal arm 128 will have moved away from switch terminal contact surface 154 thereby opening the previously defined electrical circuit and deenergizing the solenoid coil 116. Consequently, an atmospheric bleed or vent to conduit 42 is again reestablished rendering vacuum motor 21 diaphragm 31 inactive. Therefore, the ignition spark timing mechanism is once again permitted to move to a full retard position when engine operating conditions so dictate.

As the engine continues to warm, bimetal arm 128 will continue to move further to the right, as viewed in FIG. 4, until the engine temperature reaches at least 250 F. at which time bimetal arm 128 will have contacted the ramplike contact portion 156 of switch terminal member 64. As a consequence of bimetal arm 128 engaging terminal 64 contact portion 156 the previously described electrical circuit through solenoid coil 116 is again completed except that, of course, instead of having the current flow through terminal 62, it now flows through switch terminal 64. This, of course, again terminates the venting of conduit 42 to the atmosphere and enables the motor 21 diaphragm 31 to actuate the ignition spark timing a predetermined degree in the advance direction even when the engine is at a curb-idle condition.

As shown by FIGS. 1 and 2, the engine temperature warning light 74 is in circuit between switch terminal 66 and the source of electrical potential 94. Accordingly, when the engine water or metal temperature reaches, for example, 212 F., bimetal arm will have moved generally to the left so as to engage the inclined contact portion 158 of switch terminal 66. This, in turn, completes the electrical circuit through bulb 74 causing it to become energized.

In the above, the expression engine water or metal temperature was used in order to thereby clearly define the fact that even though the engine is one that is air cooled or even one which, for some reason, has lost some of its liquid coolant, the switch assembly 60 is nevertheless effective for rapidly sensing engine temperatures and creating in accordance therewith appropriate output responses.

In internal combustion engines employing a liquid coolant, such as water, situations often arise causing the loss of such coolant. When this happens temperature-sensing switches of the prior art, as generally depicted in FIG. 8, often failed to produce a warning signal sufficiently quickly to enable engine.

shutdown prior to permanent damage to the engine. If, in FIG. 8, it is assumed that the passage 182 represents internal conduitry for the coolant then it can be seen that in the absence of such coolant (due to some undetected leakage etc.) the only ath for transmitting heat to the bimetal 184 is through the relatively long body portion 186. That is, heat from the engine must pass from engine wall portion 188, through the threaded engagement, then down the depending wall of body portion 186 and into the base or end portion 190 and finally back up the bimetal 184. It has been determined that this extended path for the travel of heat is such as to cause a time delay between the moment the engine reaches a critical temperature and the time that the bimetal 184 reaches to it as to permit the engine to far exceed its safe operating temperature and thereby cause permanent damage.

Accordingly, as shown in comparison in FIG. 9, in the preferred embodiment of switch assembly 60, the housing 120 is made as short as possible so as to have the end wall 136 in close proximity to the engine wall portion 188 thereby greatly reducing the distance which heat must travel before causing the internally situated bimetal 126 to react thereto.

As also depicted by FIGS. 1 and 2, a transmission actuated switch 48 is provided in order to cause the previously described predetermined ignition timing advance to occur even though the engine temperature is greater than 60 F. and less than 250 F. Even though various kinds of switching mechanisms are of course available for this function, for purposes of illustration the switch assembly 48 has, in FIG. 2, been depicted as being a pressure responsive switch sensitive to the hydraulic pressures as may occur within an automatic type of transmission assembly 22.

Switch 48 would be so situated and calibrated as to be responsive to a range of hydraulic pressures created by the transmission assembly 22 during periods of engine and vehicle acceleration as, for example, from road speeds of 10.0 miles per hour to possible 50.0 miles per hour. During such occurrences, switch contact member 191 would engage contacts 52 and 50 thereby completing the electrical circuit energizing solenoid coil 116. This, as previously described with reference to the closure of switch terminals 62 and 64 causes the motor 21 diaphragm 31 to effect the predetermined degree of ignition timing advance thereby resulting in a more complete combustion of the fuel-air mixture so as to reduce the degree of emission of unburned hydrocarbons into the atmosphere through the exhaust system.

In the preferred form of the invention it is contemplated that the bimetallic element 126 of switch assembly 60 will be so formed as to exhibit thermal lag or hysteresis. That is, the element 126, including arms 128 and 130, will be formed of material having a known value of electrical resistance. Therefore, when arm 128 and 130 engage, for example, terminal contact portions 156 and 158, respectively, electrical current will pass through such bimetallic arms and in so doing cause the generation of heat within the thermostatic arms. Such an increase in the heat within the bimetallic arm causes an increase in the force with which such arm is held against the cooperating terminal contact portion.

For example, if it is assumed that bimetal arm 128, having been heated by the engine to 250 F has just engaged terminal contact portion 156, it can be seen that a flow of electrical current will occur through bimetal arm 128. As set forth above, such current will cause the bimetal arm 128 to become further heated which, in turn, causes the bimetal arm 128 to want to move further to the right as viewed in FIG. 4. However, since, as seen in FIG. 4, further movement of bimetal arm 128 to the right is effectively precluded by terminal contact portion 156, the result is that the bimetal arm 128 exhibits a greater force against contact portion 156.

Accordingly, it can be seen that in such an arrangement even without any increase in engine temperature beyond the assumed 250 F., that the bimetal arms 128 will remain closed against terminal contact portion 156 until such time as when the engine temperature decreases by, for example, 3 to 8 below the assumed predetermined critical temperature of 250 F. This, of course, would be dependent upon the degree of thermal lag desired; that is, the selection of material forming, as well as the geometry of and load through, the bimetal 126 would determine the electrical resistance which, in turn, would determine the amount of heat induced into the bimetal by the current flow.

In any event, it can be seen that the provision of such thermal lag generating means prevents the engine from hunting". That is, without such an inherent hysteresis, the engine once attaining the assumed 250 F. temperature would experience a change in the ignition spark timing (as previously discussed) and such a change in timing would result in a decrease in engine temperature causing the bimetal to open the associated electrical circuit whereupon the ignition timing would revert to its previous condition again causing the engine to become heated to the 250 F. temperature. This, of course, results in an objectionable and unstable engine operation. However, if provided with the thermal lag as discussed above, engine operation is made much more stable.

The thermal lag discussed above may also be accomplished by mechanical means. That is, as is generally well known in the art, an embossment may be mechanically drawn into the bimetal arm so as to provide a snap acting movement of the bimetal arms once the critical temperature is reached. As a consequence of such snap action, an extra amount of contact pressure or force is realized by mechanical means which must be overcome by a definite change in a lowering temperature before the associated circuit is opened.

FIG. 10 illustrates another embodiment 60a of the switching assembly 60 of FIGS. 4 and 5. All elements in FIG. 10 which are like or similar to those of FIGS. 4 and 5 are identified with like reference numbers provided with a suffix, a.

As shown in FIG. 10 the cover or cap member a is formed with indentations or recesses 192 and 194 as to receive therein cooperating locating-type tabs 196 and 198 of terminal members 200 and 202. Therminal member 200 has a laterally disposed body portion 204 held in abutting engagement with the upper surface of cover 140a as by a pair of crimped-under clamping arms 206 and 208 formed integrally with body 204 and extending downwardly through suitable passages 210 and 212 formed in cover 140a as shown, for example, in FIG. 11.

A first contact member 214 is provided in the form of a screw member threadably engageable with a threaded hole formed in body 204 while a second contact member 216 is illustrated as being of a pinlike configuration received through, in press-fit relationship, a cooperating hole 218 formed in terminal body 204. As discussed with reference to FIG. 4, the temperature at which engagement between terminal contacts 214 and 216 and bimetal arm 1280 can be selected by vertical adjustment of contacts 214 and 216 relative to bimetal arm 128a, as, for example, by threadably rotating screw contact 214 or axially forcing pin contact 216. Such adjustments would, of course, be made prior to the pouring of the dielectric filler material a.

Terminal member 202 also has a body 220 situated atop cover 14011 but, instead of clamping arms, is provided with an integrally formed tubular portion 222 depending downwardly through an aperture 224, formed in cover 140a, in a manner enabling the lower end thereof to be generally peened-over against the lower surface of cover 140a as illustrated at 226. Tubular portion 222, being internally threaded, receives therein a threadably adjustable contact 228 which, as contacts 214 and 216, may be adjusted in order to select the temperature at which bimetal arm 130a will engage contact 228. The seal 152a, as seal 152 of FIG. 4, also closely engages the terminal contact members as well as clamping arm 206 and 208 so as to further assure that no filler material 170a will flow into cavity 134a prior to its hardening. As illustrated at 230 and 232, the ends of the bimetal arms 128a and 1300 may be bent or formed as to have a generally inclined contacting surface which is complementary to that of the cooperating terminal contacting surface. This would serve to enchance the quality of the contact between cooperating elements and thereby reduce the electrical resistance at the point of contact engagement. FIG. 12, fragmentarily, illustrates another arrangement by which a switch terminal can be secured to the cover 140a. In this arrangement, a terminal 234 has a body portion 236 situated atop the cover 140a and secured thereto as by an eyelet 238 passing through an aperture 240 in cover 140a. The interior of the eyelet 238 may, of course, be threaded as to therein receive the adjustable contact member 228. The upper ends of the terminals 200, 202, and 234 may, of course, be of any appropriate configuration and, to that extent, may be formed to have a fiat spadelike shape as generally shown in FIG. 6 at 174. In employing the switch assembly 60a of FIG. within the environment of FIG. 2, instead of switch assembly 60, it can be seen that terminal 200 would be connected to conductor 56 while terminal 202 would be connected to conductor 70 of FIG. 1. There would be no need for parallel branches in the external circuitry (as achieved by conductor 68 of FIGS. 1 and 2) because the parallel paths are provided for internally of the switch assembly 60a as by terminal portion 204 and adjustable contact members 214 and 216. FIG. 10a, generally a modification of the embodiment of FIG. 10, illustrates a housing 121 having a cover formed, for example, out of electrically nonconducting material so as to provide a plurality of recesses or chambers 125 and 127 which respectively contain terminals 129 and 131. (The terminals may actually be partially molded within the cover 123 so as to pro vide a degree of mechanical retention therebetween.) The lower leg 133 of terminal 129 has contact members 135 and 137 threadably engaged therewith while leg 139 of terminal 131 has a contact member 141 threadably engaged therewith. After the contacts 135 and 137 and 141 are properly adjusted, a sealing or locking filler material 143 (similar to, for example, 170a) may be placed into chambers 125 and 127. The entire cover can be secured in place as by peened portion 145 formed against an annular seal 147 thereby holding the cover 123 against the shoulder 149.

The invention has thus far been disclosed employing a pair of bimetal arms to achieve specified switching functions. However, it should be apparent that the switch assembly 60 or 60a may include any number of such temperature-positioned contacting arms. For example, as fragmentarily shown in perspective in FIG. 13, the bimetallic element 242 may have a plurality of arms 244, 246, 248 and 250 each of which may be employed for making and breaking various related circuits. Further, all of such arms may be formed integrally with a common base or bight portion 252, which can be secured to the base of the switch housing as shown generally by portions 138 and 138a of FIGS. 4 and 10.

In FIG. 14, all elements like or similar to those of the Preceding FIGS. are identified with like reference numbers provided with a suffix, b. As can be seen, the operation of the solenoid assembly would be altered so as to have the solenoid valve member 110b normally closed, by a compression spring 115, thereby preventing any atmospheric bleed to conduit 42. As shown, terminal 62b would be connected to coil 1l6b by a conductor 254 while terminal 64b would be connected to ground 256 as by suitable means 258. Switch housing 120b is shown containing a plurality of bimetallic elements 260 and 262 of which 260 is of a U-shaped configuration having arms 264 and 266 joined by a bight portion 268, while 262 comprises a base 270 with a single arm 272. The elements 260 and 262 may be retained as by peened-over post 138b passing through base portions 268 and 270; however, as shown, elements 260 and 262 are electrically isolated from each other by a bushing member 274, situated generally about the post 13812, and including a radiating flange 276 serving to prevent contact between bases 268 and 270.

The operation of the invention as generally depicted in FIG. 14 is briefly as follows. Arm 264 of bimetal 260 would remain open, with respect to terminal contact surface 154b, at engine temperatures less than the previously assumed lower critical temperature of 60 F. and be closed against contact surface l54b at engine temperatures equal to or greater than 60 F. while arm 266 would remain closed against terminal contact surface 156b during all engine temperatures less than the previously assumed upper critical temperature of 250 F. and become open (that is, move away from) with respect to contact surface 156b at engine temperatures equal to or greater than the said 250 F.

Accordingly, if it is first assumed that the engine is at 55 F the circuit through solenoid coil 116b will be open because bimetal arm 264 is not engaged with terminal contact portion l54b. Therefore, coil 1161: will remain deenergized enabling spring 115 to hold valve member closed to atmosphere. This, in turn, as previously described with reference to FIGS. 1, 2, 4 and 10, permits vacuum from port 43 to actuate motor 21 diaphragm 31 causing the previously described predetermined ignition timing advance. However, as engine temperature increases beyond the assumed lower critical temperature of 60 F. bimetal arm 264 moves generally to the left so as to engage the terminal contact portion l54b thereby completing the circuit from ground 256, terminal 64b, bimetal am 266, bimetal base 268, bimetal arm 264, terminal 62b, coil 116b, electrical source 94b and back to ground at 96b. This, of course, energizes solenoid coil 116k causing valve 11% to be moved against the resistance of spring thereby opening conduit means 42 (FIG. 1) to communication with the atmosphere. As previously described with reference to FIGS. 4 and 10, such an atmospheric bleed renders motor 21 diaphragm 31 further ineffective and returns the complete control over the ignition timing mechanism to motor 20 diaphragm 27.

If engine temperature should continue to rise to equal or exceed the assumed upper critical temperature of 250 F., bimetal arm 266 will, with such increasing temperatures, tend to move to the right until, at the attainment of said 250 F. temperature, arm 266 moves out of engagement with terminal contact portion 1561;. (Of course, during this time arm 264 is also being heated and tends to move further to the left. However, because of the constraining effect of terminal contact portion 154b the upper end of arm 264 is not permitted to move further to the left and, therefore, the entire arm 264 may assume a bowed configuration much as that depicted by bimetal arm 266 in FIG. 14).

As a consequence of the disengagement between bimetal arm 266 and terminal contact portion 156b, the circuit leading to the solenoid coil 1161: is once more opened causing the valve member 1l0b to go closed so as to apply vacuum, from port 43, to motor 21 diaphragm 31 resulting in again establishing the predetermined degree of ignition timing advance even with the engine operating at curb-idle conditions. If the switch assembly 60b were employed in combination with the transmission pressure switch 48 of FIG. 2, terminal 52 of FIG. 2 would be electrically connected conductor 254 of FIG. 14 or to an appropriate terminal of the solenoid valve assembly 44b.

Of course, if the engine were employing a liquid coolant, such as water, and engine temperature reached, for example, 212 F., bimetal arm 272 would have moved to the right so as to engage and complete an electrical circuit through terminal contact portion l58b thereby energizing the warning light 74.

FIG. 15, an enlarged fragmentary cross-sectional view taken generally on the plane of line 15-15 of FIG. 14, typically illustrates a further improved arrangement for accommodating the terminal members through the dielectric cover b. As shown, the passageways or slots as typically illustrated by 140b is of a size so as to closely receive therein the body of terminal 62b. However, a longitudinally extending crowned portion 278, formed on the sidewall 280 of the slot 14212 is of a size as to afford a degree of interference to the otherwise free motion of the terminal 62b within the passageway l42b. As a consequence, the terminals are frictionally held wherever positioned and the crowned portion 278 further serves to fill some of the otherwise free space between the passageway and terminal thereby offering substantial resistance to the flow of filler material b therethrough.

FIGS. 16, 17, 18, and 19 illustrate another embodiment 600 of the switching assembly 60 or 60b of FIGS. 4 or 14. All elements in FIGS. 16-49 which are like or similar to those of the preceding FIGS. are identified with like reference numbers provided with a suffix, c.

As shown, the chamber l34c contains a bimetal 282 having an arm portion 284 and a base 286 by which it is secured as by a peened-over post 288 formed integrally with the end wall 1360 of housing 1200. The bimetal arm 284 is provided with oppositely disposed laterally extending support arms 290 and 292 which, in carry generally tubular dielectric bumpers 294 and 296 (which may actually be coatings applied onto the arms 290 and 292).

In addition to the bimetallic element 282, the chamber 134a contains a contact assembly 298 having a base 300 with spaced contact arms or levers 302 and 304 extending upwardly from the base which, as generally shown in FIGS. 16 and 17 may be secured to the housing as by a pair of peenedover posts 306 and held thusly in electrically isolated relationship with respect to the housing 120c and posts 306 as by a suitable dielectric member 308.

With reference to FIG. 16, as engine temperature increases, as sensed by bimetal arm 284, the arm 284 both moves to the left and, at the same time, starts to become somewhat bowed so as to have the upper portion 310 thereof further to the left than the medial portion in the vicinity of lateral arm 290, 292. As can be seen in FIGS. 17 and 18, terminals 640 and 62c are laterally spaced from each other so as to permit the free passage therebetween of the upper portion 310 of bimetal arm 284.

Accordingly, as movement of bimetal arm 284 to the left continues, bumper or abutment arm 296 will first engage lever contact 304 generally at the bulging portion 312. Upon further temperature rise, the movement of bimetal arm 284 causes corresponding movement of lever contact 304 until the upper portion 314 thereof engages the inclined contact surface l54c of terminal 620. At this time, however, bumper or abutment arm 294 has not yet engaged the other lever contact 302 which has its upper end 316 in engagement with inclined contact surface 1560 of terminal 64c.

Therefore, if switch assembly 60c were substituted for the switch assembly 60b of FIG. 14, with terminal 620 connected to conductor 254, terminal 64c connected to conductor 258 and terminal 660 connected to conductor 70b, it can be seen that the electrical circuit through coil 116b would be completed causing valve member 1101: to be opened against the resistance of spring 115. This, of course, as discussed with reference to FIG. 14, vents conduit means 42 to the atmosphere thereby preventing vacuum source 43 from having any effect on motor 21 diaphragm 31 and permitting the ignition spark timing mechanism, as controlled by motor 20 diaphragm 27, to experience a full retard condition if, of course, engine operation so dictates.

Accordingly, if it assumed that portion 314 of lever contact 304 engages terminal contact surface l54c when engine temperature is equal to or greater than a lower critical temperature of 60 F. then it becomes apparent that at engine temperatures less than 60 F. the electrical circuit to solenoid coil 1l6b is open thereby enabling the vacuum supplied by port 43 to activate motor 21 diaphragm 31 thereby establishing the previously described predetermined degree of advance in the ignition spark timing mechanism of distributor 18.

As engine temperature increases, bimetal arm 284, of course, continues to become more bowed with upper end 310 becoming progressively disposed further to the left. However, the rate of movement to the left of abutments 290 and 292 is resiliently resisted by the lever contact 304 which undergoes, yieldingly, some degree of elastic deformation as the bimetal arm and abutment 292, due to increasing heat, move toward the left. This action continues until the engine temperature reaches some assumed upper critical temperature of, for example, 250 F. at which time bimetal arm 284 and abutment 292 will have sufficiently deflected lever contact 304 so as to have, with abutment arm 290, engaged lever contact 302 and forced the upper portion 316 thereof away from terminal contact portion 1560. This again opens the electrical circuit to solenoid coil 1161; thereby producing the same results as when the engine temperature was less than the lower critical temperature of 60 F. and lever contact 304 was open with respect to terminal contact portion 1540.

Of course, due to the bowing of the bimetal arm 284, the upper portion 310 thereof can pass between the spaced terminals l58c and l54c and engage the contact surface 1580 of terminal 66c so as to thereby close an electrical circuit from conductor 70b through ground 180;. The temperature at which such is achieved will, of course, depend on the calibration of the bimetal arm 284, the vertical position of terminal contact portion 158e, as well as the location of the terminal 66c (that is, its proximity to terminals 620 and 640).

In view of the preceding it can be seen that the invention disclosed provides a novel and improved arrangement, as well as various embodiments of a novel and improved electrical switching assembly, for exercising an overriding type of control function over the conventional ignition timing mechanism, in order to reduce unburned hydrocarbons emitted by the engine exhaust while preventing damage to the engine because of the attainment of certain predetermined critical operating temperatures.

As a further improvement, it is contemplated that the free ends of, for example, bimetal arms 128 and 130 may be formed as illustrated in FIG. 20. That is, the ends 151 and 153 of arms 128 and 130 may be bent and tipped or capped with a highly electrically conductive material such as silver in order to form contact portions 155 and 157. Such silver may be deposited on the outside surface of the formed portions 151 and 153 or, formed as an inlay therein. FIG. 21 typically illustrates a further form of the bimetal members wherein the arms of the bimetal terminal have a straight end 159 with a generally bent-over cap 161 which may be formed of highly conductive material, such as silver, and secured to the arm end 159 as by soldering.

The invention has been disclosed as having circuitry directly interconnecting such elements as the solenoid coil 116, the warning light 74 and the switch terminals. It should be apparent that the terminals of the switches could instead be connected to control circuitry associated with suitable relay means for, in turn, actually controlling the opening and closing of related power circuitry.

Further, although the electrical circuitry has not been shown, it should be apparent that switches according to the invention may be equally well able to control such other enginedriven accessories as, for example, the air-conditioning compressor 24. That is, it is often desirable to prevent the operation of the vehicle air-conditioning system when the engine is below some predetermined lower critical temperature. Accordingly, this could be easily achieved with the electrical switch assemblies of the invention by employing such a switch assembly to open and close related circuitry associated with an electrical clutch assembly 26 thereby effecting clutching and declutching in accordance with engine temperature.

Although only a select number of embodiments of the invention have been disclosed and described, it should be apparent that other embodiments and modifications of the invention are possible within the scope of the appended claims.

We claim:

1. A temperature-responsive electrical switch assembly, comprising a housing, an insulating member closing one end of said housing and defining a chamber within said housing, first switch contact means carried by said insulating member and having a first contact portion extending into said chamber, said first switch contact means including a second terminal portion extending beyond said insulating member externally of said chamber, electrically conductive temperatureresponsive means carried by said housing within said chamber and including a bimetallic arm with a swingable end contact surface said first switch contact means being longitudinally adjustable in order to permit movement thereof relative to said insulating member and said temperature-responsive means to a suitable position in order to enable engagement between said swingable end contact surface of said temperatureresponsive means and said first contact portion at a predetermined temperature, and means carried by said insulating member for effectively locking said first switch contact means against further longitudinal movement once said switch contact means has been moved to said position, said first switch contact means comprising an elongated electrically conductive member slidably received through said insulating member, said first contact portion comprising a contact surface formed to be inclined at an angle substantially less than 90; and with respect to the longitudinal axis of said elongated electrically conductive member, and said contact surface being adapted to at times be abuttably engaged by said swingable end contact surface of said temperature-responsive means to thereby complete an electrical circuit therethrough.

2. A temperature-responsive electrical switch assembly, comprising a housing, an insulating member closing one end of said housing and defining a chamber within said housing, first switch contact means carried by said insulating member and having a first contact portion extending into said chamber, said first switch contact means including a second terminal portion extending beyond said insulating member externally of said chamber, electrically conductive temperatureresponsive means carried by said housing within said chamber, said first switch contact means being longitudinally adjustable in order to permit movement thereof relative to said insulating member and said temperature-responsive means to a suitable position in order to enable engagement between said temperature-responsive means and said first contact portion at a predetermined temperature, means carried by said insulating member for effectively locking said first switch contact means against further longitudinal movement once said switch contact means has been moved to said position, said first switch contact means comprising an elongated electrically conductive member slidably received through said insulating member, said first contact portion comprising a contact surface formed to be inclined with respect to the longitudinal axis of said elongated electrically conductive member, said contact surface being adapted to at times be abuttably engaged by said electrically conductive temperature-responsive means to thereby complete an electrical circuit therethrough, and keying means formed by said insulating member and said elongated electrically conductive member for guiding relative motion between said elongated electrically conductive member and said insulating member.

3. A temperature-responsive electrical switch according to claim 2, wherein said keying means comprises a longitudinally extending riblike portion formed on said first switch contact means and a cooperating groove formed through said insulating member for slidably receiving said riblike portion therein.

4. A temperature-responsive electrical switch assembly, comprising a housing, an insulating member closing one end of said housing and defining a chamber within said housing, first switch contact means carried by said insulating member and having a first contact portion extending into said chamber, said first switch contact means including a second terminal portion extending beyond said insulating member externally of said chamber, electrically conductive temperatureresponsive means carried by said housing within said chamber, said first switch contact means being longitudinally adjustable in order to permit movement thereof relative to said insulating member and said temperature responsive means to a suitable position in order to enable engagement between said temperature-responsive means and said first contact portion at a predetermined temperature, means carried by said insulating member for effectively locking said first switch contact means against further longitudinal movement once said switch contact means has been moved to said position, second and third switch contact means carried by said insulating member in spaced relationship to each other and said first switch contact means, said second and third switch contact means respectively having second and third contact portions extending into said chamber, and first and second moveable contact arms situated within said chamber and electrically connected to each other, said temperature-responsive means being effective for at times abuttingly engaging said first and second moveable contact arms in order to in accordance with the temperature of said temperature-responsive means move said contact arms into and out of engagement with said second and third contact portions in order to thereby make and break an electrical circuit therebetween.

5. A temperature-responsive electrical switch assembly according to claim 4, wherein said second and third switch contact means carried by said insulating member are each longitudinally adjustable in order to permit movement thereof relative to said insulating member and said moveable contact arms to a suitable position in order to enable engagement between said moveable contact arms and said second and third contact portions at preselected temperatures.

6. A temperature-responsive electrical switch assembly, comprising a housing, and insulating member closing one end of said housing and defining a chamber within said housing, first switch contact means carried by said insulating member and having a first contact portion and a second contact portion each extending into said chamber, said first switch contact means including a second terminal portion extending beyond said insulating member externally of said chamber, electrically conductive temperature-responsive means carried by said housing within said chamber, said first and second contact portions being longitudinally adjustable in order to permit movement thereof relative to said insulating member and said temperature-responsive means to a suitable position in order to enable engagement between said temperature-responsive means and said first and second contact portions at respectively different predetermined temperatures, and means carried by said insulating member for effectively locking said first and second switch contact portions against further longitudinal movement once said switch contact portions have been moved to said position, second switch contact means carried by said insulating member and having a third contact portion extending into said chamber, said second switch contact means including a third terminal portion extending beyond said insulating member externally of said chamber, said third contact portion being longitudinally adjustable in order to permit movement thereof relative to said insulating member and said temperature-responsive means to a suitable third position in order to enable engagement between said temperature-responsive means and said third contact portion at a third predetermined temperature, means carried by said insulating member for effectively locking said third contact portion against further longitudinal movement once said third contact portion has been moved to said third position, said temperature-responsive means comprising a generally U-shaped bimetallic element having at least first and second moveable arm portions, said first arm portion being effective to alternately engage said first and second contact portions at said respectively different temperatures, said second arm portion being effective to engage said third contact portion at said third predetermined temperature, and including electrically conductive material of a predetermined electrical resistance carried only by said first moveable arm portion, said electrically conductive material being effective to become heated by the electrical current flowing therethrough whenever said first arm portion is in engagement with said first contact portion so as to thereby cause said arm portion to be urged against said first contact portion with an increasing force related to heat generated within said electrically conductive material by said electrical current flowing therethrough.

7. A temperature-responsive electrical switch assembly according to claim 6, wherein, said second terminal portion includes a bodylike base portion mechanically secured to said insulating member at a surface thereof opposite to said chamber, wherein said first contact portion of said first switch contact means comprises an externally threaded electrically conductive member operatively threadably engaged with said base portion and extending through said insulating member,

and wherein said means carried by said insulating member for effectively locking said first second and third switch contact portions comprises a moldable dielectric material effectively covering outer exposed ends of said first second and third contact portions.

8. A temperature-responsive electrical switch assembly, comprising a housing, an insulating member closing one end of said housing and defining a chamber within said housing, first switch contact means carried by said insulating member and having a first contact portion extending into said chamber, said first switch contact means including a second terminal portion extending beyond said insulating member externally of said chamber, electrically conductive temperatureresponsive means carried by said housing within said chamber, said first switch contact means being longitudinally adjustable in order to permit movement thereof relative to said insulating member and said temperature responsive means to a suitable position in order to enable engagement between said temperature-responsive means and said first contact portion at a predetermined temperature, means carried by said insulating member for effectively locking said first switch contact means against further longitudinal movement once said switch contact means has been moved to said position, and second switch contact means carried by said insulating member and having a first contact portion extending into said chamber, said second switch contact means including a second terminal portion extending beyond said insulating member externally of said chamber, said second switch contact means being longitudinally adjustable in order to permit movement thereof relative to said insulating member and said temperature responsive means to a suitable position in order to thereby enable initial engagement between said temperature-responsive means and said first contact portion of said second switch contact means at a second temperature different from said predetermined temperature, said temperature-responsive means comprising a bimetallic element electrically insulated from said housing and having first and second arm portions respectively effective for engaging said contact portions of said first and second switch contact means.

9. A temperature-responsive electrical switch assembly, comprising a housing, an insulating member closing one end of said housing and defining a chamber within said housing, first switch contact means carried by said insulating member and having a first contact portion extending into said chamber, said first switch contact means including a second terminal portion extending beyond said insulating member externally of said chamber, electrically conductive temperatureresponsive means carried by said housing within said chamber, said first switch contact means being longitudinally adjustable in order to permit movement thereof relative to said insulating member and said temperature-responsive means to a suitable position in order to enable engagement between said temperature-responsive means and said first contact portion at a predetermined temperature, means carried by said insulating member for effectively locking said first switch contact means against further longitudinal movement once said switch contact means has been moved to said position, and second and third switch contact means carried by said insulating member in spaced relationship to each other and said first switch contact means, said second and third switch contact means respectively having second and third contact portions extending into said chamber, said temperature responsive means comprising a bimetallic element with first and second moveable arm portions, said first moveable arm portion being effective to at times alternately engage said first and second contact portions of said first and second switch contact means, and said second moveable arm portion being effective to at times engage said third contact portion of said third switch contact means. 

1. A temperature-responsive electrical switch assembly, comprising a housing, an insulating member closing one end of said housing and defining a chamber within said housing, first switch contact means carried by said insulating member and having a first contact portion extending into said chamber, said first switch contact means including a second terminal portion extending beyond said insulating member externally of said chamber, electrically conductive temperature-responsive means carried by said housing within said chamber and including a bimetallic arm with a swingable end contact surface said first switch contact means being longitudinally adjustable in order to permit movement thereof relative to said insulating member and said temperature-responsive means to a suitable position in order to enable engagement between said swingable end contact surface of said temperature-responsive means and said first contact portion at a predetermined temperature, and means carried by said insulating member for effectively locking said first switch contact means against further longitudinal movement once said switch contact means has been moved to said position, said first switch contact means comprising an elongated electrically conductive member slidably received through said insulating member, said first contact portion comprising a contact surface formed to be inclined at an angle substantially less than 90* ; and with respect to the longitudinal axis of said elongated electrically conductive member, and said contact surface being adapted to at times be abuttably engaged by said swingable end contact surface of said temperature-responsive means to thereby complete an electrical circuit therethrough.
 2. A temperature-responsive electrical switch assembly, comprising a housing, an insulating member closing one end of said housing and defining a chamber within said housing, first switch contact means carried by said insulating member and having a first contact portion extending into said chamber, said first switch contact means including a second terminal portion extending beyond said insulating member externally of said chamber, electrically conductive temperature-responsive means carried by said housing within said chamber, said first switch contact means being longitudinally adjustable in order to permit movement thereof relative to said insulating member and said temperature-responsive means to a suitable position in order to enable engagement between said temperature-responsive means and said first contact portion at a predetermined temperature, means carried by said insulating member for effectively locking said first switch contact means against further longitudinal movement once said switch contact means has been moved to said position, said first switch contact means comprising an elongated electrically conductive member slidably received through said insulating member, said first contact portion comprising a contact surface formed to be inclined with respect to the longitudinal axis of said elongated electrically conductive member, said contact surface being adapted to at times be abuttably engaged by said electrically conductive temperature-responsive means to thereby complete an electrical circuit therethrough, and keying means formed by said insulating member and said elongated electrically conductive member for guiding relative motion between said elongated electrically conductive member and said insulating member.
 3. A temperature-responsive electrical switch according to claim 2, wherein said keying means comprises a longitudinally extending riblike portion formed on said first switch contact means and a cooperating groove formed through said insulating member for slidably receiving said riblike portion therein.
 4. A temperature-responsive electrical switch assembly, comprising a housing, an insulating member closing one end of said housing and defining a chamber within said housing, first switch contact means carried by said insulating member and having a first contact portion extending into said chamber, said first switch contact means including a second terminal portion extending beyond said insulating member externally of said chamber, electrically conductive temperature-responsive means carried by said housing within said chamber, said first switch contact meanS being longitudinally adjustable in order to permit movement thereof relative to said insulating member and said temperature responsive means to a suitable position in order to enable engagement between said temperature-responsive means and said first contact portion at a predetermined temperature, means carried by said insulating member for effectively locking said first switch contact means against further longitudinal movement once said switch contact means has been moved to said position, second and third switch contact means carried by said insulating member in spaced relationship to each other and said first switch contact means, said second and third switch contact means respectively having second and third contact portions extending into said chamber, and first and second moveable contact arms situated within said chamber and electrically connected to each other, said temperature-responsive means being effective for at times abuttingly engaging said first and second moveable contact arms in order to in accordance with the temperature of said temperature-responsive means move said contact arms into and out of engagement with said second and third contact portions in order to thereby make and break an electrical circuit therebetween.
 5. A temperature-responsive electrical switch assembly according to claim 4, wherein said second and third switch contact means carried by said insulating member are each longitudinally adjustable in order to permit movement thereof relative to said insulating member and said moveable contact arms to a suitable position in order to enable engagement between said moveable contact arms and said second and third contact portions at preselected temperatures.
 6. A temperature-responsive electrical switch assembly, comprising a housing, and insulating member closing one end of said housing and defining a chamber within said housing, first switch contact means carried by said insulating member and having a first contact portion and a second contact portion each extending into said chamber, said first switch contact means including a second terminal portion extending beyond said insulating member externally of said chamber, electrically conductive temperature-responsive means carried by said housing within said chamber, said first and second contact portions being longitudinally adjustable in order to permit movement thereof relative to said insulating member and said temperature-responsive means to a suitable position in order to enable engagement between said temperature-responsive means and said first and second contact portions at respectively different predetermined temperatures, and means carried by said insulating member for effectively locking said first and second switch contact portions against further longitudinal movement once said switch contact portions have been moved to said position, second switch contact means carried by said insulating member and having a third contact portion extending into said chamber, said second switch contact means including a third terminal portion extending beyond said insulating member externally of said chamber, said third contact portion being longitudinally adjustable in order to permit movement thereof relative to said insulating member and said temperature-responsive means to a suitable third position in order to enable engagement between said temperature-responsive means and said third contact portion at a third predetermined temperature, means carried by said insulating member for effectively locking said third contact portion against further longitudinal movement once said third contact portion has been moved to said third position, said temperature-responsive means comprising a generally U-shaped bimetallic element having at least first and second moveable arm portions, said first arm portion being effective to alternately engage said first and second contact portions at said respectively different temperatures, said second arm portion being effective to engage said third contacT portion at said third predetermined temperature, and including electrically conductive material of a predetermined electrical resistance carried only by said first moveable arm portion, said electrically conductive material being effective to become heated by the electrical current flowing therethrough whenever said first arm portion is in engagement with said first contact portion so as to thereby cause said arm portion to be urged against said first contact portion with an increasing force related to heat generated within said electrically conductive material by said electrical current flowing therethrough.
 7. A temperature-responsive electrical switch assembly according to claim 6, wherein, said second terminal portion includes a bodylike base portion mechanically secured to said insulating member at a surface thereof opposite to said chamber, wherein said first contact portion of said first switch contact means comprises an externally threaded electrically conductive member operatively threadably engaged with said base portion and extending through said insulating member, and wherein said means carried by said insulating member for effectively locking said first second and third switch contact portions comprises a moldable dielectric material effectively covering outer exposed ends of said first second and third contact portions.
 8. A temperature-responsive electrical switch assembly, comprising a housing, an insulating member closing one end of said housing and defining a chamber within said housing, first switch contact means carried by said insulating member and having a first contact portion extending into said chamber, said first switch contact means including a second terminal portion extending beyond said insulating member externally of said chamber, electrically conductive temperature-responsive means carried by said housing within said chamber, said first switch contact means being longitudinally adjustable in order to permit movement thereof relative to said insulating member and said temperature responsive means to a suitable position in order to enable engagement between said temperature-responsive means and said first contact portion at a predetermined temperature, means carried by said insulating member for effectively locking said first switch contact means against further longitudinal movement once said switch contact means has been moved to said position, and second switch contact means carried by said insulating member and having a first contact portion extending into said chamber, said second switch contact means including a second terminal portion extending beyond said insulating member externally of said chamber, said second switch contact means being longitudinally adjustable in order to permit movement thereof relative to said insulating member and said temperature responsive means to a suitable position in order to thereby enable initial engagement between said temperature-responsive means and said first contact portion of said second switch contact means at a second temperature different from said predetermined temperature, said temperature-responsive means comprising a bimetallic element electrically insulated from said housing and having first and second arm portions respectively effective for engaging said contact portions of said first and second switch contact means.
 9. A temperature-responsive electrical switch assembly, comprising a housing, an insulating member closing one end of said housing and defining a chamber within said housing, first switch contact means carried by said insulating member and having a first contact portion extending into said chamber, said first switch contact means including a second terminal portion extending beyond said insulating member externally of said chamber, electrically conductive temperature-responsive means carried by said housing within said chamber, said first switch contact means being longitudinally adjustable in order to permit movement thereof relative to said insulating member and said tempeRature-responsive means to a suitable position in order to enable engagement between said temperature-responsive means and said first contact portion at a predetermined temperature, means carried by said insulating member for effectively locking said first switch contact means against further longitudinal movement once said switch contact means has been moved to said position, and second and third switch contact means carried by said insulating member in spaced relationship to each other and said first switch contact means, said second and third switch contact means respectively having second and third contact portions extending into said chamber, said temperature responsive means comprising a bimetallic element with first and second moveable arm portions, said first moveable arm portion being effective to at times alternately engage said first and second contact portions of said first and second switch contact means, and said second moveable arm portion being effective to at times engage said third contact portion of said third switch contact means. 